DefinePK

Research Objective

To examine the ovipositional preferences of the fall armyworm (FAW), Spodoptera frugiperda, on Brassica rapa L., B. oleracea var. capitata, and Zea mays L. under laboratory conditions, and to assess the impact of adult diet on reproductive parameters.

Methodology

The study involved culturing FAW larvae collected from maize fields on maize, mustard, and cabbage under laboratory conditions. Oviposition responses were assessed through no-choice and choice bioassays using seedlings of these host plants. Reproductive parameters (pre-oviposition period, oviposition period, post-oviposition period, and adult longevity) were recorded. Additionally, the effect of different adult diets (honey solution, yeast solution, honey + yeast solution, protein solution, and honey + protein solution) on oviposition was investigated using a maize strain of FAW. Statistical analysis was performed using one-way ANOVA and the Least Significant Difference (LSD) test.

Methodology Flowchart

                        graph TD;
    A[Collect FAW larvae from maize fields] --> B[Rear larvae on maize, mustard, cabbage];
    B --> C[Conduct oviposition bioassaysno-choice & choice];
    C --> D[Record egg counts and cluster sizes];
    B --> E[Assess reproductive parameters];
    E --> F[Record pre-oviposition, oviposition, post-oviposition periods, adult longevity];
    B --> G[Rear maize strain FAW on different adult diets];
    G --> H[Assess fecundity and reproductive parameters];
    D & F & H --> I[Statistical Analysis - ANOVA, LSD];
    I --> J[Draw Conclusions];                    

Discussion

The study highlights the strong ovipositional preference of FAW for maize, even when larvae are reared on other host plants. This suggests that olfactory cues from maize play a crucial role in host selection. While FAW can survive and develop on secondary host plants like mustard and cabbage, their primary preference for oviposition remains maize. The findings also emphasize the significant impact of adult diet on fecundity and oviposition period, suggesting that nutritional supplementation can enhance reproductive output, which is beneficial for mass-rearing FAW in laboratory settings. The research indicates that FAW in Pakistan has not significantly adapted to other host plants as primary oviposition sites.

Key Findings

- Host plant species significantly influenced FAW oviposition preference.
- The highest egg count (675 ± 32.4 eggs) was recorded on maize in no-choice experiments.
- In choice experiments, FAW moths consistently showed a strong preference for ovipositing on maize, regardless of the host plant they were reared on.
- Neither the mustard strain (139 ± 37.3 eggs) nor the cabbage strain (37.0 ± 4.6 eggs) laid the highest number of eggs on their respective host plants in choice experiments.
- The honey + protein solution diet resulted in the highest fecundity (1188 ± 64.84 eggs).
- The oviposition period was significantly influenced by adult diet, with the honey + protein solution diet yielding the longest oviposition period.
- Larval diet did not significantly affect pre-oviposition, post-oviposition periods, or adult longevity.

Conclusion

The fall armyworm in Pakistan exhibits a strong ovipositional preference for maize, which is not solely determined by larval feeding suitability on alternative host plants. Adult diets, particularly those rich in protein and sugars like honey and protein solutions, significantly enhance egg production. Effective management strategies for FAW on maize should consider monitoring other host plants within similar families to enable timely pest control interventions.

Fact Check

- The study was conducted under laboratory conditions at the Department of Entomology, Sindh Agriculture University (SAU), Tando Jam.
- FAW larvae were collected from maize fields surrounding the SAU experimental area in Tando Jam (25.42260 N; 68.53700 E).
- The highest egg count recorded was 675 ± 32.4 eggs on maize.

Mind Map